JPH0124615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding machine, and more particularly to a mold clamping device driven by a motor.

(Prior art) In a conventional injection molding machine, a method of using a servo motor as a drive source for a mold clamping device is already known (for example, Japanese Patent Application Laid-Open No. 179630/1982 or Japanese Patent Application Laid-open No. 179630/1983). (See Publication No. 62030). This is an injection molding machine in which both the injection device and the mold clamping device are driven by one large servo motor. And the mold clamping device is
The rotational force of the servo motor is transmitted as a linear motion to the screw shaft via the transmission shaft and gears, and the movable mold connected to the screw shaft is moved linearly forward or backward relative to the fixed mold. Thus, the mold opening/closing action and the mold clamping action are performed.

(Problem to be solved by the invention) By the way, the mold opening/closing action of the mold clamping device has to rotate at high speed (possible with low torque) in order to improve work efficiency.
On the other hand, during mold clamping, high torque (low speed rotation is possible) is required to obtain a high quality product. Therefore, although it is theoretically possible to obtain the dual effects of high torque and high-speed rotation with a single servo motor as in the past, in practice it requires a very large servo motor. In particular, as disclosed in JP-A-58-179630 or JP-A-58-62030,
In a system in which not only the mold clamping device but also the various functions of the injection device are performed by the same servo motor, the size of the servo motor has to be increased.
For this reason, most injection molding machines using servo motors are small machines, and large injection molding machines are hydraulically driven or are hydraulically driven and motor driven.

In view of the above-mentioned problems, the present invention has been devised to make it possible to obtain a mold clamping action with a large mold clamping force and a mold opening/closing action at high speed by using a commonly used motor as a drive source, and which can also be used for large-scale injection molding. The technical problem to be solved is to provide a mold clamping device that can also be applied to machines.

(Means for Solving the Problem) The technical means for solving the above problem consists of a fixed platen fixed on the machine base, and a fixed platen that is opposite to the fixed platen and is slidably attached via a guide bar. A movable platen is connected to the movable platen by a ball screw type feeding mechanism, and one of the screw shaft and nut in the ball screw type feeding mechanism is rotatably attached to the fixed platen, and the other is rotatably attached to the movable platen. Both the screw shaft and the nut are individually driven by two systems of gear drive mechanisms having different reduction ratios using a motor as a drive source.

(Operation) The rotational force from the servo motor is selectively transmitted to both the screw shaft and the nut via two systems of gear drive mechanisms. That is, when opening and closing the mold, the movable platen is moved forward or backward via a gear type drive mechanism with a small reduction ratio, while the mold clamping action is performed via a gear type drive mechanism with a large reduction ratio. As a result, a high-speed mold opening/closing action and a large mold clamping force can be obtained.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. FIG. 4 shows the entire injection molding machine, in which a mold clamping device A is installed on one side of the machine stand 1, and an injection device B is installed on the other side. The mold clamping device A includes a pair of fixed platens 2 that are erected facing each other on a machine base 1, and a movable platen that is slidably attached to four guide bars 3 that are suspended horizontally on the fixed platens 2. 4, and molds 5 and 6 are fixed to opposing surfaces of the fixed platen 2 and the movable platen 4, respectively (on the right side in the figure).

Further, the movable platen 4 and the other fixed platen 2 (on the left side in the figure) are connected by a ball screw type feeding mechanism 7. That is, as shown in FIG. 1, a screw shaft 8 is attached to the movable platen 4,
A nut 9 is attached to the fixed platen 2 and is screwed into the screw shaft 8 via a ball 10. The base of the screw shaft 8 is press-fitted into a cylindrical boss portion 12a of a driven gear 12 rotatably supported by the movable platen 4 via a bearing 11, and is prevented from coming off by a stopper plate 13. On the other hand, the nut 9 is similarly press-fitted into a cylindrical boss portion 15a of a driven gear 15 rotatably supported by the fixed platen 2 via a bearing 14.

Thus, the screw shaft 8 and the nut 9 are individually rotated by a single servo motor 16 installed on the machine base 1 via two gear drive mechanisms 17 and 18 with different reduction ratios. It's becoming like that. That is, the drive mechanism 17 on the screw shaft 8 side includes a drive pinion 20 spline-fitted to a spline shaft 19 rotated by a servo motor 16 to enable axial movement; an intermediate large gear 22 that is fixed and meshes with the drive small gear 20;
an intermediate small gear 2 fixed on the intermediate shaft 21 and meshing with a driven gear 12 integrated with the screw shaft 8;
3, and the screw shaft 8 is adapted to be rotated in the same direction as the rotational direction of the servo motor 16.
Further, the intermediate shaft 21 is provided with a clutch 24 between the intermediate large gear 22 and the intermediate small gear 23, and the movable platen 4 is further provided with a brake 25 for braking the intermediate shaft 21. Although not shown, each of the gears described above is housed in a gear box fixed to the movable platen 4, and is moved together with the movable platen 4.

On the other hand, the drive mechanism 18 on the side of the nut 9 includes a drive shaft 27 connected to the spline shaft 19 via a clutch 26, a large drive gear 28 fixed to the drive shaft 27, and a rotation of the large drive gear 28. The nut 9 is configured to be rotated in a direction opposite to the direction of rotation of the servo motor 16. . The intermediate gear 2
There may be only one nut 9 and 30, in which case the rotation direction of the nut 9 will be the same as the rotation direction of the servo motor 16. Note that a brake 31 for braking the drive shaft 27 is attached to the machine base 1 or the fixed platen 2.

As is clear from the drawings, in this embodiment, the reduction ratio of the drive mechanism 17 on the screw shaft 8 side is set to a large value, while the reduction ratio on the nut 9 side is set to a small value. Note that there is no need to explain the details of the injection device B, so the details will be omitted.

This embodiment is configured as described above,
The opening and closing action of the molds 5 and 6 is performed by driving the nut 9, and the mold clamping action is performed by driving the screw shaft 8. That is, mold matching prior to injection and mold release after injection are performed by disconnecting the clutch 24 on the screw shaft 8 side and connecting the clutch 26 on the nut 9 side. 16 rotates the nut 9 at high speed via a drive mechanism 18 with a small reduction ratio;
The movable platen 4 moves forward or backward at high speed together with the screw shaft 8 to open and close the mold.

On the other hand, the matched molds 5 and 6 are clamped by disconnecting the clutch 26 on the nut 9 side and connecting the clutch 24 on the screw shaft 8 side. A high thrust can be applied to the movable platen 4 by rotating the screw shaft 8 at low speed with high torque via the drive mechanism 17 having a large reduction ratio. That is,
The molds 5 and 6 are clamped with high thrust.

In addition, during mold matching, the mold is protected by reducing the rotation speed of the servo motor 16 from a high speed to a low speed just before contact, and the timing of changing the rotation speed and the mold matching are determined. The timing of switching from to mold clamping is determined based on position detection using a limit switch, magnescale, etc., timer control, or detection of the total number of revolutions of the servo motor 16.

The brake 31 on the nut 9 side is activated at or just before the end of mold alignment and mold release, while the brake 25 on the screw 8 side is activated when the molds 5 and 6 are clamped with a predetermined thrust. Later on, it is operated to maintain that state.

FIGS. 5 and 6 show other embodiments of the present invention, respectively. The embodiment shown in Fig. 5 uses dedicated motors 32 and 33 for the mold opening/closing action and the mold clamping action, respectively, and the embodiment shown in Fig. 6 uses a screw shaft. 8
By making the driven gear 12 integrated with the fan gear protrude from between the guide bars 3 as a sector gear, a larger reduction ratio can be set. In actual mold clamping work, the screw shaft 8 rotates for the purpose of generating high torque, and the amount of rotation is small. Therefore, in the embodiment shown in FIG.
It becomes possible to use an inexpensive ordinary motor that does not require rotational accuracy, and in the embodiment shown in Fig. 6, it is possible to obtain stronger mold clamping force by increasing the reduction ratio. There are advantages such as: However, in the embodiment shown in FIG. 5, the driven gear 12 is directly meshed with the driving gear 20 on the mold clamping side, and the driving gear 28 and the driven gear 15 are connected via one intermediate gear 29 on the mold opening/closing side. are engaged.

In each of the above-mentioned embodiments, the reduction ratio of the drive mechanism 17 on the screw shaft 8 side is set to a large value, and the reduction ratio of the drive mechanism 18 on the nut 9 side is set to a small value, but this setting can be reversed. In that case, the screw shaft 8 side is used for the mold opening/closing function, and the nut 9 side is used for the mold clamping function. Furthermore, the screw shaft 8 may be provided on the fixed platen 2 side and the nut 9 may be provided on the movable platen 4 side, and the motor as the drive source is not limited to a servo motor.

(Effects of the Invention) As detailed above, the present invention uses a motor as a drive source and drives both the screw shaft side and the nut side of a ball screw type feed mechanism through two drive mechanisms with different reduction ratios. This structure enables high-speed mold opening/closing action and strong mold clamping action. Therefore, unlike conventional equipment, it is possible to use a motor to drive large injection molding machines, and it also enables small injection molding machines to be driven by motors. When applied to a molding machine, the motor can be made smaller.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a drive system diagram of the mold clamping device, FIG. 2 is a view in the direction of the X arrow in FIG. 1, and FIG. 3 is a view in the direction of the Y arrow in FIG. 4 is a schematic front view of an injection molding machine, FIG. 5 is a drive system diagram of a mold clamping device showing another embodiment, and FIG. 6 is an explanatory diagram showing still another embodiment. 1...Machine base, 2...Fixed platen, 4...Movable platen, 7...Ball screw type feeding mechanism, 8...
Screw shaft, 9... Nut, 10... Ball, 16...
...Servo motor, 17, 18... Drive mechanism.

Claims (1)

[Claims] 1. A fixed platen fixed on a machine base and a movable platen opposed to the fixed platen and slidably attached via a guide bar are connected by a ball screw type feeding mechanism. At the same time, one of the screw shaft and the nut in the ball screw type feeding mechanism is rotatably attached to a fixed platen and the other to a movable platen, and both the screw shaft and the nut are driven by a motor. , and a mold clamping device for an injection molding machine which is individually driven by two systems of gear drive mechanisms having different reduction ratios. 2. The mold clamping device for an injection molding machine according to claim 1, wherein the two systems of gear drive mechanisms use a common motor as a drive source. 3. The mold clamping device for an injection molding machine according to claim 1, wherein each of the two systems of gear type drive mechanisms is provided with a motor as an independent drive source.